precision highp float;
varying vec2 texture_coords;
uniform sampler2D g_texture;
void main() {
vec4 texColor = texture2D(g_texture, texture_coords);
	   float c = (texColor.r + texColor.g + texColor.b)/(3.0);
	   float r = c;
	   float g = c;
	   float b = c;
	   gl_FragColor = vec4(r,g,1, 1);
}